274 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



The oesophagus is distinctly marked off from the buccal cavity, 

 though the direct continuation of it. The oesophagus runs at first up- 

 ward and forward, and then, making an elbow, continues upward and 

 backward until it attains the middle of the upper half of the head, just 

 above and behind the brain, or supra-oesophageal ganglion, where it 

 gradually widens both its transverse and vertical diameters to form the 

 crop, where the digestion proper begins, according to Professor Felix 

 Plateau. The crop is marked off anteriorly by a slight constriction. 

 The walls of the oesophagus, and, indeed, of the whole digestive canal 

 as far as the ventricle, are of a brownish-red color, and thrown up 

 into folds covered by a hard chitinous layer, and armed with projecting 

 spines and processes. In the oesophagus the ridges run nearly longi- 

 tudinally, and are not so high nor so well marked as in the crop. 



The crop is that part of the intestinal canal which extends back- 

 ward from the oesophagus through the three thoracic segments. It 

 consists of two parts. The anterior, larger, and horizontal division lies 

 In the posterior portion of the head and in the prothorax. Its diameter 

 is especially variable, for its walls are capable of great distension. When 

 filled with food its diameter becomes greater than any other part of the 

 digestive tract j when empty, on the other hand, it contracts, and may 

 become of less size than the ventricle. The posterior portion of the 

 crop has hardly more than half the diameter of the front division j it 

 tapers slightly backwards, as it descends through the two hinder seg- 

 ments of the thorax, and terminates in the rudimentary proven- 

 triculus (Kaumagen), which can be recognized by the six large folds or 

 chitinous teeth. In the grasshoppers this organ is very much reduced 

 in size, and appears, rather, merely as the terminal portion of the crop 

 than as an independent structure. It is interesting to note this analogy, 

 because in most other members of the order of Orthoptera the Kauma- 

 gen is very large, distinct, and of a very complicated structure.^^ 



The anterior division of the crop is characterized by transverse ridges, 

 the crests of which are covered by very hard chitine, which is thrown 

 up into short, stout, and sharp spines that point backward. The office 

 of the spines is evidently to aid the passage of the food down the diges- 

 tive canal, and to prevent its regurgitation. The ridges are all trans- 

 verse, but the anterior ones are wider than the others. Each ridge ex- 

 tends only one-third or one-half of the way around the crop, and finally they 

 incline from above backward, while the posterior ridges are longer, nar- 

 rower, and more nearly vertical in their course. At the point where the 

 second division of the crop begins, there intervenes between the two 

 parts a space in which the ridges are very irregular, running straight 

 for very short distances only, and forming numerous sharp angles. In 

 this manner the direction of the ridges from being transverse becomes 

 first slightly, then' very irregular, until they finally become longitudinal, 

 which direction is characteristic for the posterior division of the crop. 



■isSee American Naturalist, July. 1877, and Dr. Wilde's TJntersuchungen iiber den Kaumagen der 

 Orthopteren. Arckivfiir Naturgeschichte, 1817, He/tl, p. 135. 



